Metals are often used for hard tissue replacement such as bone. Illustrative metals used for implants include: stainless steel, titanium, chrome, and cobalt alloys. An osteoconductive environment must be established in a suitable bone replacement. The osteoconductive material provides scaffolding for cellular migration, cellular attachment, and cellular distribution. Bone will integrate into the osteoconductive material and secure the bone replacement. Metal implants often loosen at the interface with bone. Metal implants fail even when the surface of the implant is coated with an osteoconductive material. One reason for metal implant failure is the vastly different material properties compared to bone.
Carbon fiber reinforced carbon composites are also used as candidate bone replacement material because of their comparable rigidity to cortical bone. A comparison of bone rigidity to bone replacement material rigidity is insufficient to determine bone replacement suitability. A more detailed comparison of bone to the bone replacement material is needed to determine a suitable bone replacement. Material properties of ultimate strength, yield strength, and elastic modulus need to be compared between potential bone replacement materials and bone.
Soft tissue attachments to other soft and hard tissues can use resorbable and/or non resorbable materials. Materials such as silicon base elastomers and poly lactic acid are not currently formed with engineered and tailored volumetric porosity for in-growth of soft biological tissue or attachment to such tissue. Each tissue type has its own unique in-growth requirements. Those requirements include appropriate volumetric space and morphology.
What is needed is a suitable morphologically appropriate volumetric porosity for hard and soft tissue replacement and/or attachment material other than metal. Preferable materials possess three features:                1. the material is biocompatible and may have been used in previous biomedical applications such as joint prostheses, bone plates, dental posts, and long bone replacement; and        2. the material can be cast, allowing it to be fabricated into complex shapes.        3. the material's volumetric porosity is interconnected and capable of being arranged in a porosity gradient in one or more dimensions.        